Rubber composition and method of producing the same



Patented be. 15, 1929 I UNITED STATES PATENT. OFFICE WILLIAM OJGEER ANDHARRY L.- FISHER, OF AKRON, OHIO, ASSIGNORS TO THE B. I.

GOODRICH COMPANY, OF NZ EW YORK, N. Y., A CORI'ORATION OF NEW YORKRUBBER COMPOSITION AND METHOD OF PRODUCING THE SAME No Drawing.

' '15'Fisher, Patent No. 1,668,235, filed January 14, 1924, Patent No.1,668,236, filed January 17, 1924, and Patent No; 1,668,237, filed April14, 1924, processes are described for the prep-' arationtof balata-likeor shellac-like deriva- 2o tives of rubber, by reacting thereon with asulfuric acid, a sulfonic" acid, a sulfonyl chloride, or mixturesthereof, all of which may be described as rea ents having the generalformula R SO 1% wherein R represents an 2 organic radical or a hydroxygroup and X represents chlorine or a hydroxy group. We now find thatthese reagents react with the resins, proteins and other naturalimpurities in the raw rubber and thereby transform so them intowater-soluble products. By washing such balata-like 'or shellac-likerubber de= rivatives with hot water on a rubber washing mill or by othersuitable means, substantially all of the water absorbing impuri- .tiesoriginally present in the crude rubber and all excess of reagents areremoved and an improved product is obtained having a lower degree ofmoisture absorption, such product being .better adapted for use in elec-9 trical insulation and the like than the unpurified material.

Our invention also comprises the removal of resins, proteins or otherimpurities from crude rubber and reacting thereon with sulfuric acids,sulfonic acids, sulfonylchlorides, or the-like, whereby there isprovided an impro ed class of rubber derivatives substan-.

' tia y free from moisture absorbing constituent's. In such processes itis still desirable to wash the reaction product for the removalApplication filed May 20, 1924. Serial No. 714,734.

of further impurities such as excess of reagents.

The purification of the crude rubber as above mentioned may beaccomplished, for example,-by milling or otherwise forming an emulsionof rubber with such alkaline reagents as sodium carbonate, sodium hy-'droxide, sodium oleate or the like and heating the mixture in open steamor by boiling in water for from 10 to 36 hours. The modified proteinsand resins, and the excess of alkah or other impurities, may then beremoved by washing;

In the preparation of gutta percha substitutes as set forth in thecopending applica-. vtion of W. C. Geer, Serial No. 708,585, filed April23, 1924, it was found desirable to modify the plasticityof the reactionproducts of rubber, such as are hereinbefore mentioned, by milling intothem certain percentages of crude rubber. We now find that the waterabsorption of the mixture may be substantially reduced by (1) preparingthe rubber derivatives from purified rubber, by (2) washing the reactionproducts to remove water soluble impurities and by (3) modifying theirphysical properties by the addition of Ipurified crude rubber.

xamples of our preferred procedure are as follows: I

Example I.A balata-like der1vat1ve of rubber is prepared b mixing 100parts by weight of purified ru ber w th 5 to parts of phenol sulfonicacid, and the m1x 1s heated in a compact mass in an oven maintained at atemperature of 286 F. for SIX hours.

(The use of unpurified rubber in this.exam-.

ple requires from 7 to 7.5 parts of phenol sulfonic acid to produce aproduct of s1m1lar physical properties.) Our final productpossesses ahigher degree of purlty and has a lower moisture absorption, than theproduct as prepared from unpurified rubber.

We preferably wash the reactlonproduct, as derived from either crude orpurified raw rubber, for the further removal of Water absorbingimpurities.

E mam Ze lL-A gutta percha substltute 1s prepare by mixing 180 parts ofthe balatalike product of'Example I with 20 parts of purified rubber,providing a tough, flexible material which can be calendered, tubed,

molded or otherwise treated for the preparation of molded insulation orother articles.

This product has a lower moisture absorption than the product preparedfrom crude rub- Example I I I .A shellac-like obtained by mixingpurified ru ber100, p-toluene sulfonic acid8, and sulfuric acid (sp. gr.1.84)-2, parts by weight, and heating the mass for 7 hours at 190 F.followed by 10 hours at 266 F. This product is more nearly transparentin thin layers, breaks with a conchoidal fracture, grinds easier and isless hygroscopic than the product as prepared from unpurified rubber.

- Example IV.-An improved gutta percha substitute is prepared'by mixing42.5 parts of a shellac-like rubber derivative, such as described inExample III, with 32.5 parts of a balata-like derivative of rubber, suchas described in Example I, and adding thereto 25.0

, stances are eliminated, and we do not wholly parts of purified rubber.A gutta perchalike material is thus produced which ismuch lesshygroscopic than the product similarly obtained from unpurified rubberas described lGll the above identified application of W. O.

as to procedure whereby the hygroscopic sublimit our claims .to theexact procedure described.

" We claimz- 1. The method of producing a rubber composition having lowmoisture absorption whlch comprlses effecting a reactlon between.

- rubber and a reagent having the general formula RSO X, wherein-1trepresents an organic radicalor a hydroxy group and X represents.chlorine im a hydroxy group, and removing water soluble constituents bywashmg the reaction product.

3, The method of producing a rubber composition having low moistureabsorptionwhich comprises effecting a reaction between rubber and areagent having the general forh g mula RSO *X, wherein R represents an60 organicradical or'a hydroxy group and X represents chlorine ora-hydroxy group, and

mlxmg purified raw rubber with the product.

4, The method of producing arubber composition having low moistureabsorption which comprises efiecting a reaction between grod'uct is 1Our invention may be variously modified rubber and a reagent having thegeneral formula R SO X, wherein It represents an organic radical or ahydroxy group and X represents chlorineor a hydroxy group, washing thereaction product to remove water purified raw rubber.

5. The method of producing a rubber composition having low moistureabsorption which comprises effecting a reaction between purified rawrubber and a reagent. having the general formula R- SO X, whereinRrepresents an organic radical or a hydroxy group and X representschlorine oia hydroxy group, and mixing purified raw rubber with theproduct.

6.' The method of producing a rubber comsoluble impurities andm1x1ngtherewith position having .low moisture absorption H whichcomprises (1) removal of natural impurities present in crude rubber, (2)efle'cting a reaction between the rubber and a reagent having thegeneral formula RSO X,

wherein R represents an organic radical or a hydroxy group and Xrepresents chlorine or a hydroxy group, washin' the reaction product toremove water solu 1e impurities and (4) mixing therewith purified rawrub- \ber. Y

7. A step in'the preparation of rubber com i positions having a lowmoisture absorption and prepared by reacting on rubber with a reagenthaving the general formula R SO X, wherein R represents an organicradical or a hydroxy group and X represents chlorine or a hydroxygroup,which comprises removing hygroscopic, non-rubber constituentsnaturally'present in crude rubber.

-8. A composition of matter. comprising a reaction product of rubberwith a reagent having the general formula RSO X wherein represents anorganic radical or a hydroxy group and X represents chlorine or ahydroxy-group, said composition of matter being relatively free fromproteins.

9. A composition of matter comprising a reaction roduct of rubber with areagent having t e general formula R SO X wherein R represents anorganic radical or a hydroxy group and X represents-chlorine or ahydroxy group maid composition being rela-' tivelyfree from thenon-rubber constituents naturally present in raw rubber.

10. A composition of matter comprising a reaction roduct of rubber with:a"reagent having t e general formula R SO X where-in R represents anorganic radical or a v hydroxy group and X represents chlorine or aydroxy group, said composition of matter being relatively, free fromhygroscopic constituents.

11'. A composition of matter comprising a reaction product of rubberwith a sulfonic acid, from proteins.

12. A; composition of matter. comprising a said compositionbeingrelatively 'free I r reaction product of rubber with a sulfonic acid,said composition being relatively free from the non-rubberconstituentsnaturally present in raw rubber.

13. A composition of matter comprising a reaction product of rubber witha sulfonic' acid, said composition being relatively free fromhygroscopic constituents.

14. A composition of matter comprising a reaction product of rubber withp-toluenesulfonic acid, said composition being relativly free fromproteins.

15. A composition of matter comprising a reaction product of rubber\with p-toluene sulfonic acid, said composition being relatively freefrom the non-rubber constituents naturally present in raw rubber.

16. A composition of matter comprising a reaction product of rubber withp-toluene sulfonic acid, said composition being relatively free fromhygroscopic constituents.

In witness whereof we have hereunto set our hands this 17th day of May,1924.

WILLIAM C. GEER. HARRY L. FISHER.

